A twin-reflector antenna is comprised of a main reflector 10, a secondary reflector 11 and a radiating source 12 placed in front of the secondary reflector. The radiating source can operate in circular or linear monopolarization or bipolarization, in frequency monoband or frequency multiband mode. The radiating source 12 emits electromagnetic waves illuminating the secondary reflector 11 which reflects the electromagnetic waves towards the main reflector 10. The electromagnetic waves are then reflected by the main reflector 10 towards Earth, in the form of one or more beams, of which the footprints on the ground form a single-spot or multi-spot coverage respectively, according to the number of emitted beams.
When the twin-reflector antenna comprises a short focal length F, i.e. when the F/D ratio between the focal length F of the main reflector and the diameter D of the main reflector is between 0.8 and 1.1, it is possible to install two twin-reflector antennas 15, 25 on the same lateral side 30 of a satellite, by disposing the two twin-reflector antennas on either side of the median line 13 dividing the lateral side into two areas, as shown, for example, in FIG. 1. However, this type of antenna comprises reduced radio-frequency performance.
When the twin-reflector antenna comprises a long focal length, i.e. when the F/D ratio is greater than 1.1, the installation on the same side of a satellite is currently possible only by using deployable secondary reflectors installed on the Earth side of the satellite, the Earth side being the side of the satellite oriented towards the Earth. This poses problems of arrangement, since the Earth side of the satellite is generally intended for the installation of antennas and equipment linked to the overall purpose of the satellite. Furthermore, these antennas are complex and require the installation of a deployment system for the secondary reflectors, which increases the cost.
To the best of our knowledge, no solution currently exists for arranging two twin-reflector antennas, at least one of the two antennas having an F/D ratio greater than 1.1, on the same side of a satellite due to the size of the secondary reflectors. The problem is that this limits the number of antennas that can be installed on a satellite and therefore limits the number of tasks that can be performed.